EP0083460B1

EP0083460B1 - Agricultural implement

Info

Publication number: EP0083460B1
Application number: EP19820201644
Authority: EP
Inventors: Ary Van Der Lely; Cornelis J. G. Bom
Original assignee: C Van der Lely NV
Current assignee: C Van der Lely NV
Priority date: 1981-12-22
Filing date: 1982-12-21
Publication date: 1989-01-25
Anticipated expiration: 2002-12-21
Also published as: NL8105770A; EP0083460B2; DE3279383D1; NL188013B; EP0083460A1

Description

The invention relates to an agricultural implement comprising a frame connectable to a tractor and a protective member which, with respect to the intended direction of travel of the implement, screens at least a foremost part of a working member of the implement in an operative, first position of said working member, and said protective member is movable into a second operative position relative to said frame by moving the working member into a second position.
An agricultural implement of this kind is known from FR-A-2,063,497 (Figs. 8, 9) which describes a haymaking machine with rake members, the distance between the axes of operation of said rake members being'adjustable. Protective members screening the rake members maintain their relative position with respect to said rake members upon adjustment, providing quite the same shielding function.
DE-A-1,582,369 shows a protective member which shields the mowing elements of a mowing machine. The mowing elements can be folded up into a transport position, a position wherein the protective member would be an obstacle. Therefore said protective member is folded down relative to the mowing elements by hand into a second position wherein it has lost its shielding function.
The invention has for its object to provide the performance of a further task of the protective member in order to utilize it more effectively.
According to the invention, the implement comprises adjusting means by which the relative position of the protective member with respect to the working member is automatically changed by moving the working member into its second position.
In this way new openings appear for a supplementary use of the protective member as, for example, a shieJding device for other parts of the machine, the performance of a function differing from its original function or for creating an advantageous dimension of the implement in its second position.
For a better understanding of the invention and to show how the same maybe carried into effect reference will be made by way of example to the accompanying drawing.

Fig. 1 is a plan view of a first embodiment in the form of a rotary haymaking machine attached to a tractor.
Fig. 2 is an enlarged view of part of Fig. 1.
Fig. 3 is a side elevation of the machine shown in Fig. 1.
Fig. 4 is a partly sectional elevational view taken on the lines IV-IV in Fig. 2.
Fig. 5 is a partly sectional elevational view taken on the lines V-V in Fig. 2.
Fig. 6 is a partly sectional elevational view taken on the lines VI-VI in Fig. 2.
Fig. 7 is a plan view of the machine of the preceding Figures in a transport position.
Fig. 8 is a plan view of a second embodiment of the invention in the form of a mower attached to a tractor.
Fig. 9 is a partly sectional side elevation taken on the lines IX-IX in Fig. 8.
Fig. 10 is a side elevation of a rotary haymaking machine attached to a tractor in a further embodiment of the invention.

Fig. 1 shows a plan view of a rotary haymaking machine hitched to a tractor in a first embodiment of the agricultural implement in accordance with the invention, whilst the parts most important for the invention are shown in Fig. 2 on an enlarged scale. Apart from the screening members and their mode of fastening in accordance with the invention, the further part of the rotary haymaking machine is shown in a general view.
The rotary haymaking machine 1 comprises a main frame beam 2, which is substantially horizontal and extends transversely of the direction of travel A. The main frame beam 2 is rigidly secured by means of supports 3 to a trestle 4 in the form of an inverted U provided near the top and near the two lower ends with connecting means 5, to each of which can be fastened one of the arms 6 of the three-point lifting device of a tractor 7. Of the tractor 7 only the rear part of the tractor is shown, comprising a cab 8 and mudguards 9 covering ground wheels-of the tractor on the top and rear sides.
Near the two ends of the main frame beam 2 rake members 10 are journalled so as to be drivable in known manner from the tractor 7 about upwardly directed rotary shafts 11. Each of the rake members 10 comprises in this embodiment a plurality of spokes 12, to the ends of which are secured groups of tines 13, the tines being first downwardly inclined away from the ends of the associated spokes 12 and being then outwardly bent over so as to be directed substantially parallel to a plane at right angles to the rotary shaft 11 concerned. Therefore, viewed in the direction of the associated rotary shaft 11 the tine ends are located at a distance below the free end of a spoke 12. To the ends of the spokes 12 of the rake members may, of course, also be secured tines which extend downwards or which are outwardly and downwardly inclined in the operative position. Near each end of the main frame beam 2 is provided a bearing for a pivotal shaft 14, which is directed substantially horizontally and parallel to the direction of travel A. About each of the pivotal shafts 14 is pivotable a frame beam 15, which, in operation, is substantially in line with the frame beam 2. Near the outermost end of each frame beam 15 is journalled a rake member 10, which can be driven by means of the tractor about a rotary shaft 16 extending parallel to the rotary shaft 11 during operation. The structures of the two outermost rake members 10 are identical to those of the two inner rake members 10 and may, therefore, be provided with tines or groups of tines extending outwardly or with groups of tines directed fully downwards, in which case the tine ends are located at a distance below the spokes 12.
The rotary hay-making machine 1 may be provided with pairs of swath boards which can be set both in an operative position and an inoperative position with respect to the rest of the machine.
Each of the four rake members 10 is supported in known manner by a ground wheel, which may in this case be freely pivotable about the associated rotary shaft 11 or 16 respectively.
During operation the two frame beams 15 together with the outermost rake members 10 fastened to them can freely turn up and down about the associated pivotal shaft 14 in order to permit the outermost rake members 10 to match unevenness of the ground.
A second function known per se of the pivotal shafts 14 lies in that for transport purposes the two outer frame beams 15 with the outermost rake members 10 fastened to them can be tilted up in a manner such that the frame beams 15 extend upwardly. This latter possibility provides a smaller width of the machine during transport.
In the rotary haymaking machine shown in Fig. 1 tilting up the two frame beams 15 with the outermost rake members 10 fastened thereto is performed by a hydraulic ram 17 connected with the hydraulic system of the tractor 7 and controllable from the cab 8. The hydraulic ram 17 is a single-action ram; after hydraulic energization of the ram its piston rod slides inwardly into the cylinder space. The end of the cylinder itself is fastened to the frame beam by means of an upwardly directed support 18 rigidly secured to one of the frame beams 15, whereas the end of the piston rod is pivotally connected in a similar manner with the frame beam by means of an upwardly directed support 19 rigidly secured to the other frame beam 15.
After energization of the hydraulic ram 17 the two frame beams 15 are turned upwards towards one another into a position in which further turning of the frame beams 15 with respect to the main frame beam 2 is prevented by a stop or stops. In a known embodiment the main frame beam is provided with two resilient stops so that in the transport position the two frame beams 15 are in resilient contact with the stops so that, when the hydraulic pressure in the ram 17 is obviated, the resilient stops impart to the two frame beams 15 an outward impulse after which the frame beams 15 with the rake members fastened thereto turn downwards into the working position, whilst the hydraulic fluid flowing out of the cylinder is conducted away in a controller manner through a relatively light-structured relief valve. The invention proposes inter alia a simple replacement of these resilient stops, as will be explained more fully hereinbelow.
Each of the frame beams 15 is provided with a locking pin 20, which is horizontal and directed forwardly, whilst near each locking pin 20 at the end of the main frame beam 2 a lock bolt 21 is provided, which automatically falls around the neighbouring pin 20 during the upward turn of the frame beam 15 so that during transport the frame beams 15 are fixed in place.
To each of the lock bolts 21 is fastened a rope extending into the cab 8. When the driver wants to turn the frame beams 15 out of the transport position into the working position, the hydraulic ram 17 is briefly energized so that the driver can lift the lock bolts by pulling the ropes, after which the frame beams 15 are released to move downwards. Each of the outer parts of the haymaking machine 1, said parts having each a frame beam 15 and an outermost rake member 10, is provided with a screening member 22, which is substantially horizontal and is located, viewed with respect to the direction of travel, at least in this embodiment, in front of the outermost rake member 10. The bracket-shaped screening member 22 embraces the sides and, in addition, the front of the foremost half of the rake member 10 concerned in conformity to prevailing provisions. This protection is intended to prevent persons standing at the front or a side of the rake member from coming into contact with the driven tines and from thus being injured.
The mode of fastening of the bracket 22 is illustrated in Figs. 2 to 6.
Each of the frame beams 15 is provided at relatively spaced places with supporting plates 23 and 24 respectively, which are directed upwards and in the direction of travel A in the working position of the machine and which protrude in front of the frame beam 15. To the front of each of these plates is rigidly but releasbly secured a plate- shaped support 25 and 26 respectively, these supports 25 and 26 projecting to the front away from the plates 23 and 24. The supports 25 and 26 are, therefore, also rigidly secured with respect to the frame beam 15. Each of the supports 25 and 26 has on the rear side a cavity to receive a tubular shaft 27, the centre line 28 of which is parallel to that of the frame beam 15 and thus extends substantially horizontally and transversely of the direction of travel A during operation. From Fig. 2 it is apparent that to the two ends of the shaft 27 is rigidly secured the bracket 22 embracing the front part of the frame member 10. The bracket 22 together with the shaft 27 can turn in the space bounded by the parts 23, 25 and 24, 26 respectively, in which space the shaft 27 is journalled as a pivotal shaft.
Referring to Figs. 2 and 6, the shaft 27 is provided with a plate 29, which is parallel to the plate-shaped support 25, but, in contrast to the plate 25, is rigidly secured to the shaft 27. The plate 29 is located on the side of the support 25 away from the support 26 (at a short distance from said support) and projects forwardly beyond the shaft 27, as will be seen in Fig. 6.
To the plate 25 is rigidly secured a pin 30 perpendicular to the plate 25 and projecting for a given distance in the direction of the plate 29.
In the support 25 as well as in the support 26 is provided a recess 31, through which passes a torsion bar 32 substantially parallel to the centre line 28. This torsion bar 32 extends, viewed in the outward direction, (Fig. 2) beyond the plate 26 up to a plate-shaped clamp 33 which is rigidly secured to the shaft 27. The torsion bar 32 is bent back through 180° at the area of the clamp 33 and the bent-back end is located in the clamp 33, which is rigidly secured to the shaft 27. The other end of the torsion bar 32 extends through the recess 31 in the supporting plate 25 and is bent over in forward direction through 90° directly on the inner side of the plate 25 to form a rod portion 34. The rod portion 34 formed by the end of the torsion bar 32 is in contact with the pin 30 rigidly secured to the plate 25 near its free end (at a distance from the recess 31 in the plate 25) (Fig. 6).
From Figs. 4 and 6 it is apparent that the rod portion 34 is upwardly inclined away from the recess 31, whereas the end near the clamp 33 is directed substantially horizontally or slightly downwardly. This means that the torsion bar 32 is prestressed. Since the rod portion 34 is supported with respect to the frame beam 15 via the pin 30, the support 25 and the supporting plate 23, the stressed torsion bar 32 tends to exert via the clamp 33 a torsional moment on the outermost end of the shaft 27 and the bracket 22 in upward direction. However, this is prevented since upon an upward turn of the bracket 22 and the shaft 27 the plate 29 rigidly secured to the shaft 27 will come into contact with the pin 30. Therefore, the bracket 22 and the shaft 27 being integral herewith have an internal bias tension which prevents the basically pivotable bracket 22 from rattling in a troublesome manner in the working position shown in Figs. 2 to 6.
To the supports 3 (Fig. 1) is secured a horizontal rod 35 extending transversely of the direction of travel and having at both ends stops formed by the two limbs 36 and 37 of an abutment pipe 38 bent through about 90°. The limb 36 of the pipe 38 is disposed, viewed in a direction transverse of the direction of travel A, at a short distance inside the inner boundary of the bracket 22 and is directed substantially vertically. The other limb 37, viewed in the direction towards its free end, is outwardly and rearwardly inclined and, as will be seen from Fig. 2, it is located below the inner part of the bracket 22. In this situation the above-mentioned bracket 22 having a bias tension during the operation of the machine is located at a relatively small distance above the limb 37 of the abutment pipe 38. The bracket 22 can turn downwards against the effect of the torsion bar 32 until the inner boundary of the bracket 22 strikes the limb 37. The precaution is taken with a view to persons coming into contact with the bracket 22: if the bracket 22 could turn freely downwards, said person would be in direct risk of contacting the rotating rake member 10. The stop 37 prevents this free downward turn and continues protecting. When the hydraulic ram 17 is actuated, the two frame beams 15 with the rake members 10 journalled thereon turn upwards, as stated above, in order to obtain a transport position in which the machine has a small width. During this upward turn the inner part of each bracket 22 comes into contact with the upwardly extending limb 36 of the stop 38. Upon a further turn of the frame beam 15 the bracket 22 is turned downwards with respect to the frame beam 15 (or rather outwards, if it is already in the upwardly turned position) into the final position shown in Fig. 7, in which the torsion bar 32 is fully or almost fully stressed. The force exerted by the torsion bar 32 is, in the position shown in Fig. 7, in equilibrium with the force exerted by the ram 17. In this final position the piston and the piston rod of the ram find themselves a stop with respect to the cylinder wall. From Fig. 7 it is apparent that the foremost part of the bracket 22 is located in a plane located beyond the plane of the tine ends of the outermost rake members 10, viewed with respect to the vertical plane of symmetry of the rotary haymaking machine. The plane going through the outermost ends of the tines of these outermost rake members is designated in Fig. 7 by reference numeral 39. It is thus ensured that persons located at the side of the travelling combination of tractor and haymaking machine are protected from contact with the tine ends of the outermost rape members.
Therefore, also in this second position the screening member is effective.
The displaced position of the bracket 22 shown in Fig. 7 results also in the advantage that, when the frame beams 15 are turned up, the bracket does not come into contact with tractor parts.
Referring to Fig. 7, reference numeral 22' designates the position, indicated by broken lines, in which the bracket 22 would be located, if the position of this bracket with respect to the frame beam 15 were maintained in the working state. In this case the bracket would have come into contact with tractor parts, in this case the mudguards 9. This involves that in accordance with the idea of the invention the machine can be attached at a smaller distance from the tractor or the lifting device 6 so that the position of the centre of gravity of the machine is improved with respect to the tractor.
A third advantage of the construction embodying the invention resides in that, as stated above, in the transport position of the haymaking machine the bracket 22 engages with spring tension the upright limb 36 of the abutment pipe 38 so that the reactive force is an outwardly directed force exerted on the frame beam 15, which is substantially vertical in the transport position. After, as described above, the tractor driver has lifted the lock bolts 21 by means of the ropes, the frame beams 15 with the outermost rake members 10 fastened thereto are urged outwardly by the spring tension produced by the brackets 22, after which the frame beams 15 and the outermost rake members can lower further into the working position by their own weight. As a result, the above-mentioned resilient stops can be dispensed with, since their function is taken over by the bracket 22.
It will be obvious that the use of screening members automatically displaceable by turning up outermost machine parts is not limited to a rotary hay-making machine; they may, for example, also be employed on rotary harrows having upwardly extending rotary shafts for the harrow tines, on weed harrows, reciprocating harrows, soil cultivators having horizontal rotary shafts, on flail mowers and in general on agricultural implements on which screening members have to be used to protect persons from coming into contact with working members, in which one of more outermost machine parts are tilted up into a transport position or a different working position. The idea of the invention may also be applied to, for example, tilted mowing platforms of combine harvesters.
Figs. 8 and 9 show the use of a displaceable screening member on a mowing machine 40 having in known manner a trestle 41 having connecting points for attachment to the three-point lifting device of a tractor. To the trestle is fastened a carrying arm 42, which is pivotable with respect to the trestle about approximately horizontal pivotal shaft extending in the direction of travel A, the center line of which is designated by reference numeral 43. The outermost end of the carrying arm 42 is provided with a mowing part 44, which is directed, like the carrying arm 42, transversely of the direction of movement A and protrudes beyond a side of the tractor. The mowing part 44 comprises a frame beam 45, which slides along the ground during operation and in which a driving mechanism is provided for driving a plurality of adjacent cutting elements 46 rotatable pairwise in opposite senses, said elements being rotatable about upwardly extending rotary axes and arranged on the frame beam 45. The mowing part 44 is adapted to turn up and down about a pivotal shaft with respect to the carrying arm 42. The centre line of said pivotal shaft is designed by reference numeral 47 in Fig. 8. The centre line 47 is parallel to the centre line 43 and is located, as indicated in the plan view of Fig. 8, near a lateral, vertical boundary of the tractor. The driving mechanism of the cutting elements 46 is constructed in known manner. The carrying arm 42 is supported on one side of the trestle 41 by means of a overload mechanism 48. The mowing part 44 bears near the pivotal shaft 47 on the ground by means of a skid 49, which enables various sloping positions of the rotary shafts of the cutting elements 46.
Above the mowing part 44 is arranged a rod system 50, which is rectangular viewed on plan, and which, viewed on plan, surrounds at some distance the cutting elements 46 (viewed with respect to the direction of movement A) the front side, the outer side and the rear side. On these sides of the rod system 50 (which bears on the mowing part 44) a screening cloth 51 is arranged on the circumferential rods of said rod system so as to hang down from these circumferential rods and to screen the mowing part 44 on the front side, the lateral side and the rear side. The circumferential rods of the rod system 50 protect persons against contact with the rotating cutting elements, whilst the screening cloth 51 prevents disengaging cutters of the cutting elements 46 from being slung away. In the embodiment shown the rod system comprises a foremost part in the form of a bracket 52 operating as a protecting member, which is pivotable with respect to the further part of the rod system 50 about a pivotal shaft substantially horizontal, parallel to the frame beam 45 and transverse of the direction of travel A. This pivotal shaft is formed by two aligned pivotal axes 53 and 54. Near the inner side face of the bracket 52, near the pivotal axis 53, a support 55 is fastened so as to be pivotally coupled with an arm 57 of a rocker 58 by means of a rod 56 pivotally fastened to said support. The rocker 58 comprises a shaft 59 extending parallel to the frame beam 45 (Fig. 8), to which shaft the arm 57 is rigidly secured, whilst a second arm 60 is rigidly secured to the inner end of the shaft 59. From Fig. 8 it will be apparent that, viewed transversely of the direction of movement A, and viewed on plan the arm 60 is located at a distance from the pivotal shaft 47 and, viewed in a vertical direction, it is located at a higher level than said pivotal shaft 47. The free end of the arm 60 is connected by means of a flexible-element, for example, a cord or a chain 61 with a part having a stationary position relative to the pivotal shaft 47. Said part is formed by a horizontal rod-shaped carrier 62 extending transversely of the direction of travel A and being rigidly secured to a bearing housing of the pivotal shaft having the centre line 47.
To a part of the bracket 52 located. near the pivotal shaft 53 thereof is secured a second support 63, which is directed upwardly like the support 55. To the free end of the support 63 is secured a tensile spring 64, the other end of which is connected with the stationary part of the rod system 50. The tensile spring 64 tends to turn the bracket 52 upwards and maintains the element 61 in a taut state.
When the mowing part 44 is tilted up out of the working position shown in Figs. 8 and 9 about the. pivotal shaft 47 into the transport position, the element 61 exerts a downwardly directed tractive force on the arm 60 of the rocker 58, owing to the location of the ends of the flexible element 61 with respect to said pivotal shaft 47, so that the arm 57 pushes the rod 56 in the direction B and the entire bracket 52 turns downwards into a position 52' indicated by broken lines in Fig. 9. Since, when the mowing part 44 is moved into the transport position, the lifting device is also slightly lifted, the front side of the rod system 50 is displaced to the rear in the transport position with respect to its front side in the working position over a distance designated in Fig. 9 by reference numeral 65. In this way it is ensured that the mowing machine can be advanced by the distance 65 to the front with respect to the tractor, which is not possible when the front side of the rod system 50 is not automatically pivotable, since in the latter case the inner end of the rod system 50 would come into contact with the neighbouring tractor wheels or the mudguards thereof. This means that, viewed from aside, the centre of gravity of the mower can be arranged nearer the lifting device of the tractor so that a smaller type of tractor can be used for operating the mowing machine.
Fig. 10 shows a further embodiment of the idea of the invention. It relates to a rotary hay-making machine shown in a side elevation. This machine comprises a frame with one, two or more rake members 10 having spokes 12 and groups of tines 13, which may be constructed and shaped as in the first embodiment. In the case of two or more rake members 10 they are arranged on a frame beam transverse of the direction of movement A by means of bearings and upwardly directed rotary shafts. The frame beam is designated by reference numeral 66 in Fig. 10. The beam 66 is provided with a trestle 67 by means of supports 68, the trestle 67 having connecting means for attaching the trestle and hence the whole implement to the three-point lifting device of a tractor. The frame beam 66 has secured to it a protective bracket 69, which extends in front and along the sides of the rake members. The bracket 69 comprises supporting parts 70, which are rigidly secured to the frame beam 66 and extend in a forward direction from said beam. The supporting parts 70 are provided at the foremost ends with aligned hinges 71 located at a distance from the frame beam 66, which corresponds in this embodiment substantially to the radius of a circle traced by the free ends of the spokes 12. The hinges 71 are horizontal and parallel to the frame beam 66 and hence transverse of the direction of travel A. A protective member formed by the foremost part of the bracket 69 is adapted to turn up and down about the hinges 71 with respect to the rest of the implement. The part 72 of the bracket 69 provides a protection on the front side and the lateral sides against the rotating rake members. The operative position shown in Fig. 10 corresponds with a position suitable for raking crop in which the rotary shaft or shafts of the rake members 10 are in a relatively steep position so that the rake member(s) is(are) in a relatively flat position with respect to the ground.
The supports 68 and the trestle 67 are in common pivotable with respect to the frame beam 66 about a substantially horizontal pivotal shaft 73 extending parallel to the frame beam 66. To the rear side of the supports 68 is rigidly secured a rearwardly protruding arm 74, which is located perpendicularly above an arm 75 rigidly secured to the frame beam 66. The two arms 74 and 75 are pivotally interconnected by means of an upwardly extending spindle 76. By turning the spindle 76 the distance between the arms 74 and 75 and hence the position of the trestle 67 with respect to the frame beam 66 and the rake member(s) 10 can be varied. For this purpose the spindle 76 is located at a distance behind the pivotal shaft 73. By reducing the distance between the arms 74 and 75 by means of the spindle 76, the rotary shaft(s) of the rake member(s) 10 can be further inclined forwardly with respect to the ground so that the plane in which the ends of the lowermost tines 13 are rotating, is at a larger angle to the ground. Such a position is suitable for tedding crop. To a lower support 68 is secured an arm 77 extending downwards from the support and being pivotable about a pivotal shaft 78 extending parallel to the frame beam 66. The arm 77 is preferably constructed in the form of a rotary spindle so that this arm has an adjustable length. The lower end of the arm 77 is pivotable about a pivotal shaft 79 parallel to the pivotal shaft 78 and secured to a rod-shaped lever 80, which is rigidly secured to the foremost, pivotable part 72 of the bracket 69. When the machine shown in Fig. 10 is changed over from the raking position into the tedding position by actuating the spindle 76, said foremost part 72 of the bracket 69 automatically turns into the position designated in Fig. 10 by reference numeral 72' by means of the arm 77 and the lever 80. In this position the foremost part 72 of the bracket is at a relatively small height above the ground. During operation the crop lying in front of the rake member(s) is pressed against the ground by means of a guide plate 81 arranged at the front of the protective member 72 and temporarily retained. The groups of tines 13 can then comb the crop slightly fixed by the guide plate 81 so that entangled crop lying on the field is disentangled and displaced laterally or rearwardly by the rake members without the formation of entangled hay bales or clumps. For this purpose the front side of the guide plate 81, which covers the whole dimension of the bracket 69 measured transversely of the direction of movement is forwardly inclined in upward direction and rounded off at the front, whilst on the top side an additional precaution may be made, if necessary, in the form of an upright plate strip 82 or the like on behalf of the protective function of the bracket 69. In this way, by displacing part of the machine, the protective member is moved into an operative position, said operative position, in contrast to the preceding embodiments, is not related to setting a transport position of the machine.
The embodiments show that a protective bracket of an agricultural implement can perform a second and even more than two further tasks so that such a component, which originally did not have any function specific for the operation of the implement can be more effectively utilized.

Claims

1. An agricultural implement comprising a frame (2; 41, 42; 67, 68) connectable to a tractor (7) and a protective member (22; 52; 69) which, with respect to the intended direction (A) of travel of the implement, screens at least a foremost part of a working member (10; 46) of the implement in an operative, first position of said working member, and said protective member is movable into a second operative position relative to said frame by moving the working member into a second position, characterized in that the implement comprises adjusting means (36, 38; 57 to 61; 76, 78 to 80) by which the relative position of the protective member (22; 52; 69) with respect to the working member (10; 46) is automatically changed by moving the working member into its second position.

2. An agricultural implement as claimed in claim 1, characterized in that with respect to the frame (2, 42), the working member (10; 46) is pivotable upwardly from its first operative position into a transport position, said adjusting means urging the protective member (22; 51, 52) into its second operative position against resilient force (32; 64).

3. An agricultural implement as claimed in claim 2, characterized in that the adjusting means comprises stop means (38) connected to the frame and engaging the protective member (22) during at least a part of its upward movement.

4. An agricultural implement as claimed in claim 2, characterized in that the adjusting means comprises a pivotable rod system (56-60, 63) which is, as a whole, movable upwardly together with the working member (46) and which can be actuated from the frame (42).

5. An agricultural implement as claimed in claim 1, characterized in that the second position of the working member is an operative position and the protective member (69) supports crop working means (81) in either of its operative positions.